Abnormal synthesis and deposition of collagen occur in several disease states. The long range goal of this project is to characterize the normal controls of collagen synthesis and how these controls are involved in disease states. The immediate objective is to examine the collagen messenger RNA population in situations which alter the amount (hypertonic growth) or type (BrdU) of collagen synthesized by cultured chick embryo cells. A cloned DNA fragment complementary to part of the alpha 2 collagen subunit will be used as a specific probe to study the synthesis, processing and stability of collagen mRNA.